Anybody have any pics of the bowl work on a set of smallblock heads that they feel run well? Trying to get a feel for bowl shape and how much, if any, to hog out, and where. I'm concerned about taking much metal out due to adding volume to the head. But if there are areas to shape that would be helpful I'd like to know, seems like the valves are not too shrouded and I'm not going to gasket match the bowls - so I'm left wondering what the best mods are for head work. And since I'm a visual guy I thought I'd put out a request for pics, but Buick small block heads only (plenty of info on chevy heads...) Thanks
I have pics of mine, I have to upload them to the web... maybe tommarow... I'm not sure how good I did since I did a bunch of other mods to... but she'll pull strong up to 6K and probally past that if I wanted to risk tossing a rod.... After a full rebuild I'll see how high she'll go.... I ground down alot of the guide boss's (i think that's what they are called).. the radius where the runners turn down to the valves is rather sharp, so I smoothed that out a good amount... I didn't want to go to far there, since I think a water passage runs through the head in that area.... The intake runners get narrow in one spot where the casting around the head bolts are... this can be taken down a bit. You'll see some more when I post the pics. I took some before and after... This was my first head porting job, I have the porting kit from summit. It has ok directions, but not to specific... I used my dremel and my air die grinder. -Nick
I'd like to see that, too. I did mine, but that was literally 10 plus years ago! Man, am I getting old? I get the feeling that I could've "shaped" the valve guide bosses a little more than I have. Here's another question for you: When polishing the combustion chambers, I somehow got the brainstorm to eliminate the "bump" by the spark plug in the CC. Was that a mistake? Everything seems to be fine, and the car hauls, so...
i wondered about that too, but then thought about the increase in head cc (but it couldn't be more than 1-2cc increase if its taken out tho'...) but in the few blurry pics of Buick port work that i've seen it looks (as best i can tell) like that bump has been taken out. i've wondered about the bump possibly shaping the burn pattern in the head vs the squish area so that the flame burns all the way to the edge, but I've never seen anything that stated this one way or the other do you recall if you measured the head volume before and after?
Ya, ya always have to think, "Was this cast in here for a reason?" It is posable that it was simply there to make it easier to cast, like a support or something... I couldn't remember what I did to it on mine, but I looked at my pictures, and I pretty much left it alone, except for rounding it a little bit... I'll try to upload the pics tommarow
I wasn't worried about a little compression loss at the time because: The block had been decked. The heads had been resurfaced multiple times and I was using .030" copper head gaskets (thinner than the Fel Pro Blues). With the 10.25:1 pistions, I figured that I had a little compression to spare, esp. on pump gas. I had been told that the bump is there to induice "Swirl" in the cc. I know that feature is gone, but I believe that I have eliminated a possible hot spot in the combustion chambers that way. Also - the spark plugs read good. A little lean if anything...
don't knwo if that worked but try this http://www.geocities.com/buicknick72/after1.jpg http://www.geocities.com/buicknick72/before1.jpg
from a Yardley post @ http://www.v8buick.com/showthread.php?s=&threadid=2332 Here are Charlie Evan's steps for Buick head porting: 1. Bowl Blend. Blend the bottom of your machined throat cut with the cast part of your bowl. Gently enlarge your bowl down deep in the bowl around the valve guide area. 2. Valve Guides. Grind on them and reduce their size quite a bit. They are sitting smack in the middle of one of the most critical areas of the port. On the intakes they dont hurt you too much because the direction of the flow is with the gentle, natural shape of the guide boss. On the exhaust they hurt you because the first thing the air sees is that abrupt flat machined surface at the top of the guide boss. Reduce it but dont completely remove it. 3. Short Side Radius. Lay it back, lay it back, lay it back!! With your fingertip you should be able to gently slide it from the seat all the way around to the crest of the floor and feel no sharp edges or abrupt changes. This should be a smooth natural roll or turn. 4. Crest Of The Floor. At the apex, or crest, you may want to reduce it some. Generally, grinding a little of the toip here greatly increases your cross-sectional area, probably at the most critical point of the window. 5. On the intakes, youll want to grind on the head bolt boss some to thin it and again increase your cross-sectional area. 6. Also on the intakes, youll want to grind on the pushrod side quite a bit and roll that short side WALL around and down gently to the seat. This is where your air flow velocity is the greatest. 7. Steps 5 and 6 are usually roughed in using a Bridgeport in an engine shop, then finished by hand. 8. On the exhaust, dont even touch that ugly reverse pocket in the bowl. Im talking about that area where the heat riser passages are on the two center ports. Every time you fill them in with clay on the flow bench, the flow picks up. So dont grind in there and make it worse. 9. As much as I would like for it to be a pure science, there is still an element of Black Magic to the feel for porting. It is somewhat of an ART. 10. I will tell you that Newtons Laws of Motion certianly apply, especially the Law of Inertia with regards to wet flow. Also, Bernoullis Principle (Daniel 1700 1782) APPLIES. Study them. 11. If you decide to port your own heads, it would still be good to send them to a shop that has the capability to flow a Buick head accurately (most all do), when you get done and have them checked and flowed. 12. Porting takes time. Lots of it. $800 ought to give you a lot of head porting time and a good flowing set of heads. Written and submitted by: Charlie Evans, GSCA Member Automotive Machine & Performance 6235 Highway 54 Philpot, KY 42366 888-624-3848
